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An electric heater rated 220V, 1000 W is immersed into a bucket full of water....

Physics
JAMB 2009

An electric heater rated 220V, 1000 W is immersed into a bucket full of water. Calculate the mass of water if the temperature changes from 30°c to 100°c and the current flows for 300seconds. [specific heat capacity of water = 4200 jkg-1 K-1]

  • A. 4.28 kg
  • B. 42.86 kg
  • C. 1.02 kg
  • D. 7.14 kg
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Correct Answer: Option C
Explanation

The energy supplied by the heater = heater gained by the water
pt = Mc\(\Delta\)θ
1000 x 300 = m x 4200(100 - 30)
m = \(\frac{(1000 \times 300)}{4200 \times 70}\) = 1.02 kg

There is an explanation video available below.


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Explanation Video

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